The coefficient of earth pressure at rest in hydrate-bearing sediments

Abstract

The presence of hydrate alters the stress distribution in sediments. Current analyses of stress state and stress path in hydrate deposits are simplistic, and no direct measurements are available. This study presents an experimental and theoretical investigation of the coefficient of earth pressure at rest K0 in tetrahydrofuran hydrate-bearing sands. Hydrate crystals creep, and thus, measured K0 values manifest time-dependent behavior. The coefficient K0 in hydrate-bearing sediments is mainly governed by hydrate cementation at low stress and by the soil particle skeleton at high stress. Estimations of K0 based on the Poissonˈs ratio from rock physics models fail to recognize plastic deformation and decementation due to loading. Particle fabric at the maximum stress in history can be partially preserved together with certain stress locked within the sediments that can significantly increase K0 values beyond usually assumed 0.5. Therefore, high lateral stress transfer is expected in the hydrate reservoir after gas production.